<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta name="viewport" content="width=device-width, initial-scale=1.0" />
    <title>css三角</title>
    <style>
      .container {
        border: 20px solid;
        border-color: transparent transparent tan teal;
        height: 0;
        width: 0;
        /* 可以实现一个45度的扇形 */
        /* border-radius: 20px; */
      }
    </style>
  </head>
  <body>
    <div class="container"></div>
  </body>
</html>
